Methods have been developed for the detection of gases using chemical sensors such as those described in “Ferroelectric WO3 Nanoparticles for Acetone Selective Detection,” by Wang et al., Chem. Mater., 20, 4794-4796 (2008), the entire contents of which is incorporated herein by reference. Further improvements in devices and methods of making and using such devices are needed, however, to improve the accuracy thereof, particularly for diagnostic applications.